Integrity field generator blocks create an aura that protects blocks and decrease the damage transmited to the ship HP.
Each block has its own HP, which is a threshold until it breaks, which is normally its HP that it contributes to the ship (with several exceptions, but we're not going into too much detail here. For example, inner blocks have a higher break threshold to make intricate ship designs combat-viable and to make designing more fun). Damage to blocks is ALSO directed to the normal HP of a ship (health bar). What integrity fields do, is reduce both the damage that a block itself takes and the damage transmited to the ship. 
Protection of blocks inside aura: 95% (blocks inside integrity fields can take 20 times as much damage before they explode) 
Ship HP damage transmission reduction: 75% 
Each Integrity Field Generator block creates an aura with different range in the 3 axis depending on its size in that axis.
- Axis X aura radius = <block's X> * 4.65
- Axis Y aura radius = <block's Y> * 4.65
- Axis Z aura radius = <block's Z> * 4.65
The aura affects another block if it touches the block at some point, it is not needed to cover all the block size.
The aura range is calculated from the center of the block, not from its borders.